Alclad Research Articles

Characterization of Mg-Al Sheet Clad Materials Fabricated by Hot Rolling

AZ31 Mg / 5083 Al clad sheet was fabricated by the hot rolling method and its mechanical properties were investigated in this study. The tensile strength and yield strength of Mg- Al clad samples were slightly higher than that of AZ31 Mg sample, resulting in high strength 5083 Al alloy. Also, in the case of the AZ31 Mg sample, tensile strength indicated different values to the rolling directions. The thickness of interface layers between magnesium and aluminum materials increased with increasing rolling temperature. The thickness of interface layer was about 1.2 μm and 1.6 μm, respectively. The difference of thickness on the interface layer with variation of rolling temperature was attributed to promote the diffusion between magnesium and aluminum materials. The Vickers hardness of Mg-Al interface layer was around 125 Hv. The interface layer composed of hard inter-metallic phases which may act a increment of Vickers hardness depending upon its thickness.

Diffusion bonding of laser-surface-modified gamma titanium aluminide alloy to nickel-base casting alloy

γ-TiAl alloy was bonded to Ni-base casting alloy using a laser surface modification technique, and the effects of Ni–Cr–Ti–Al clad coatings on TiAl alloy/Ni-base alloy bonds were investigated. Interfacial defects in joints were restricted by Ni–Cr–Ti–Al clad coatings. The compositions and microstructures of Ni–Cr–Ti–Al clad coatings have significant effects on the thickness and shape of interfacial reaction layers, and sound joints with the high shear strength are achieved between laser-surface-remelted TiAl alloy and Ni-base alloy laser clad with a Ni 56 Cr 7 Ti 15 Al 22 coating.

Assessment of surface bonding strength in Al clad steel strip using electrical resistivity and peeling tests

Aluminium clad steel strip successfully combines the surface properties of an aluminium alloy coating with the satisfactory mechanical properties of the steel substrate. The production of Al clad steel strip by rolling, however, is a more efficient and economical approach compared with other processes. In this investigation, trilayer strips of aluminium/steel/aluminium were produced using the cold roll bonding technique. The bonding strength between the layers and the electrical resistivity of the samples were measured using a peeling test and four point probe test, respectively. The effects of reduction of thickness, the friction condition between the outer layer and rolls, and the rolling velocity on the bonding strength and electrical resistivity of the samples were assessed. Finally, it is shown that the resistivity test can be used as a non-destructive test for the evaluation of the quality of bonding between the layers of aluminium clad steel strip.

Homogenization process of the intermetallic compound layers of Al–clad iron

A homogenization process was carried out with Al–clad iron by diffusion annealing at 600, 650 and 780 °C for times ranging from 2 to 72 h. The aluminum layer was completely consumed by about 4 h with the formation of different diffusion aluminides layers. The annealing treatment at 780 °C for 72 h resulted in the formation of a homogeneous Fe–Al alloy through the foil thickness. The evolution of phase formation was examined by SEM-EDAX and X-ray diffraction techniques. Wherever it was possible TEM analysis was used.

Protective role of local Al cladding against corrosion damage and hydrogen embrittlement of 2024 aluminum alloy specimens

The present investigation aims to inquire whether Al cladding of 2024 aluminum alloy specimens could provide, additionally to the expected protection against corrosion damage, also a protection against the corrosion induced hydrogen embrittlement of the alloy. The latter is observed when bare 2024 material is subjected to laboratory exfoliation corrosion exposure also in the absence of mechanical loading. Furthermore, the study aims to ponder on the question whether local Al cladding at small regions of the specimen surface might suffice for protecting the specimen against corrosion damage and hydrogen embrittlement. The work comprises the results of an extensive experimental investigation including tensile tests on precorroded 2024 specimens protected through both complete and local surface Al cladding, metallographic and fractographic analyses as well as measurements of the hydrogen uptake during the corrosion process.

Study of mechanisms of cold roll welding of aluminium alloy to steel strip

The mechanisms of cold roll welding of aluminium alloy to steel strip has been assessed based on a study of interfacial behaviour at deformations of up to 60% together with the surface characteristics of peeled Al clad steel strip. The proposed mechanisms are applicable where the contact surfaces are degreased and then scratch brushed before the rolling deformation. According to this mechanisms the scratch-brushed layers are fractured shortly after entering the roll gap at a reduction of approximately 10%, which is about the threshold deformation for the roll bonding of aluminium to steel. The transfer cracks formed then become wider so that the distance between each coherent block increases as the rolling deformation increases through the mill. This process allows the bond to be established between the underlying areas, termed as virgin metal, of base metal, which are extruded between the cracks at the scratch brushed regions.

Microstructure of U 3Si 2 fuel plates submitted to a high heat flux

In order to gain insight on the performance limits of U 3Si 2 fuel with Al cladding, fuel plates with a fissile material density of 5.1 and 6.1 g U/cm 3 were irradiated in the BR2 reactor of SCK • CEN in Mol. The plates were intended to be subjected to severe conditions leading to a cladding surface temperature of 180–200 °C and fuel temperatures of 220–240 °C. The irradiation program was stopped after the second cycle based on the visual inspection and wet sipping tests of the elements, correspondingly showing degradations on the outer Al surfaces of the U 3Si 2 plates and the release of fission products. The maximum fuel burn-up was 29% and 25% 235U, respectively. In a PIE program the microstructural causes for this degradation are analysed. It is found that the failure of the plates is entirely related to the corrosion of the Al cladding, which has caused temperatures to rise well beyond the calculated values. In all stages, the fuel grains have retained their integrity and, apart from the formation of an interaction phase with the Al matrix, they do not demonstrate deleterious changes in their physical properties.

Transient Behavior of Low Enriched Uranium Silicide Plate-Type Fuel for Research Reactors during Reactivity Initiated Accident Conditions

Abstract This paper describes the results of transient experiments using a low enriched uranium silicide miniplate fuel for research reactor. The pulse irradiation was performed in the Nuclear Safety Research Reactor (NSRR) at the Japan Atomic Energy Research Institute (JAERI). The results obtained in this study are summarized as follows : (1) The tested fuel plates were damaged with energy depositions above 94 cal/g·fuel, but remained intact below 82cal/g·fuel. A failure threshold should therefore exist between these two values. (2) Four of the fuel plates that showed peak cladding surface temperatures <330°C were damaged by the thermal stress during quenching. These damaged fuel plates revealed small intergranular cracks that propagated perpendicularly to the axial direction of the plate, from the Al cladding surface to the fuel core, without significant dimensional changes. On the other hand, when peak cladding surface temperatures were >400°C, the test fuel plates were damaged mainly by melting of the Al cladding, accompanying significant dimensional changes. (3) The thermal stress of the damaged fuel plates calculated on the basis of the maximum transient temperature drop during quenching was greater than the tensile stress that occurred during fabrication.

Dimensional Stability of Uranium Silicide Plate-Type Reactors at Transient Condition

This paper describes the result of transient experiments using low enriched uranium silicide plate-type fuel for research reactors. The pulse irradiation was carried out at Nuclear Safety Research Reactor (NSRR) in Japan Atomic Energy Research Institute. The results obtained were: 1. At fuel plate temperature of below 400°C, a good dimensional stability of the tested fuel was kept. No fuel failure occurred. 2. At a plate temperature of about 540°C, a local crack was initiated on the AI-3%Mg alloy cladding. Once the cladding temperature exceeded the melting point of 640°C, the fuel plate was degraded much by increased bowing and cracking of the denuded fuel meat occurred after relocation of molten Al cladding. Despite of these degradation, neither fragmentation of the fuel plate nor mechanical energy generation occurred up to the cladding temperature of 971 °C. 3. At the temperatures of around 925°C, the reaction of silicide particles with molten Al in the matrix and that of cladding occurred, forming Al r...

Dimensional Stability of Low Enriched Uranium Silicide Plate-Type Fuel for Research Reactors at Transient Conditions.

This paper describes the result of transient experiments using low enriched uranium silicide plate-type fuel for research reactors. The pulse irradiation was carried out at Nuclear Safety Research Reactor (NSRR) in Japan Atomic Energy Research Institute. The results obtained were: 1. At fuel plate temperature of below 400°C, a good dimensional stability of the tested fuel was kept. No fuel failure occurred.2. At a plate temperature of about 540°C, a local crack was initiated on the AI-3%Mg alloy cladding. Once the cladding temperature exceeded the melting point of 640°C, the fuel plate was degraded much by increased bowing and cracking of the denuded fuel meat occurred after relocation of molten Al cladding. Despite of these degradation, neither fragmentation of the fuel plate nor mechanical energy generation occurred up to the cladding temperature of 971 °C.3. At the temperatures of around 925°C, the reaction of silicide particles with molten Al in the matrix and that of cladding occurred, forming Al riched U (Al, Si) compounds and Si riched (U, Si) compounds at the outermost surface of the silicide particles.

Realisation of integrated optical polarisers for Ti:LiNbO 3 with Au, Al and Ti metal cladding

TE-pass polarisers with MgO buffer layer and various metal claddings (Al, Au and Ti) have been realised. For lambda =780 nm the samples showed an extinction ratio up to 55 dB and a TM attenuation of 250 dB/cm using Al cladding.

99.99% Al/6063 alloy coextruded cryogenic beam tube

A beam tube composed of 6063 alloy aluminum with a coextruded inner surface of 99.99% pure aluminum is proposed for the Superconducting Super Collider (SSC). It has higher electric conductivity than oxygen-free pure copper at liquid-helium temperature. Thermal desorption rate is ∼10−12 Pa l/s cm2 after 150 °C 24-h baking. Dynamic gas desorption by synchrotron radiation from the inner surface at liquid-helium temperature was measured with and without magnetic field. Magnetic field reduces the pressure rise by synchrotron radiation by one order of magnitude at liquid-helium temperature. If a pure Al clad beam tube is accepted for SSC vacuum system, vacuum components of aluminum alloy which can be operated at liquid-helium temperature are needed. Dynamic bellows, nonmagnetic feedthroughs, an all metal gate valve, a compact turbomolecular pump, an automatic welding machine, and a new type of pressure monitor along the ring have been developed.

Sensitivity analyses for the secondary intermediate-energy standard neutron field at the NISUS facility

Calculations are made to investigate sensitivities of the central NISUS spectrum and reaction-rate ratios to uncertainties in the macroscopic configuration. These uncertainties include density (of graphite, borone carbide and natural uranium), impurity (moisture and 10B in graphite), abundance ( 10B natural abundance) and tolerance (in Al cladding and B 4C shell). The sensitivities to the variations in the fission cross section of 235U and 238U are also studied. In these calculations the ANISN one-dimensional transport code is used with a 37 group data set derived from the UKAEA Nuclear Data Library by the GALAXY processing code. The effects of uncertainties are studied in detail and a comparison is made between the NISUS and MOL-ΣΣ standard neutron fields.

Metal-Clad Optical Waveguides: Analytical and Experimental Study

Planar optical waveguides consisting of thin dielectric films with metal cladding have been investigated theoretically and experimentally. A computer program was devised to provide the phase and attenuation constants and wavefunctions for TE and TM modes in symmetric and asymmetric guides. Approximate expressions suitable for slide-rule calculation were also derived. Numerical results and illustrations are given for films of photoresist with Al, Ag, and Au cladding. Direct measurements of the attenuation and phase constants at 0.633 microm of numerous experimental waveguides are in reasonable agreement with theory. Attenuations <1 dB/cm, which is sufficiently small for application in devices, were measured. Calculated wavefunctions illustrate the mismatch of modes at transitions between unclad and metal-clad waveguides. Experimentally, we find substantial losses at such abrupt junctions. They can be overcome by simple tapered transitions.

真空管用Al被覆Feについて（第2報）Al Clad Feの諸性質

We obtained the following results with regard to gases from Al-clad-Fe plates: (1) The volume and the composition of gases from Al-clad-Fe plate are not different from those of the gases from iron evaporated with aluminium or from pure aluminium, but very much different from those from iron. The volume of gas from Al-clad-Fe plate is about 2 cc/100 g and 90% of the gas is pure hydrogen. (2) Heating Al-clad-Fe plates at a higher temperature, some of aluminium evaporates and it shows gettering action. (3) When heated at a lower temperature or neither silicon nor other impurities is contained in aluminium, the blackness of the surface of Al-clad-Fe plate is obvious. (4) When an Al-clade-Fe plate is practically used as the anode of a vacuum tube, the properties of Al-clad-Fe are satisfactory and the character istics of the tube are very good.